Dresden 2009 – scientific programme

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AGSOE: Arbeitsgruppe Physik sozio-ökonomischer Systeme

AGSOE 11: Economic Models and Evolutionary Game Theory III

AGSOE 11.1: Talk

Wednesday, March 25, 2009, 10:15–10:45, BAR 205

The Unexpected Birth of Cooperation in the Prisoner's Dilemma with Migration — •Dirk Helbing and Wenjian Yu — ETH Zurich, Universitätstr. 41, 8092 Zürich, Switzerland

The prisoner's dilemma models situations where it is risky to cooperate and tempting to defect (i.e. to free-ride or cheat). For this reason, it is often used to study conditions for the cooperation among selfish individuals. In the evolutionary prisoner's dilemma, the finally resulting fraction of cooperators is predicted to be zero. But what happens, if we consider effects of migration? The integration of game theoretical models and models of individual motion has recently led to agent-based models, which can describe various stylized facts in social, economic, and biological systems (such as agglomeration, segregation, turn-taking, class and niche formation). But how does migration influence the level of cooperation? We find that it can change the outcome dramatically! Directed (in contrast to random, diffusive) migration can support the formation of clusters and promote a higher level of cooperation, where conventional spatial games predict a decreasing level. We also study whether this finding is robust to varying parameters and noise. This reveals a new mechanism, how cooperators manage to resist attempts of defectors to invade cooperative clusters under various conditions. In a noisy world, success-driven migration can reach a majority of cooperators even when we assume no cooperators in the beginning and selfish behavior most of the time. This unexpected discovery shows that mobility could have been very crucial for the spontaneous birth of cooperation and (pro)social behavior.